How Long Will My Premature Baby Stay in the NICU?

Wondering how long your baby will be in the NICU and what doctors will do while she's there? While the answer varies, you can get a sense of what your baby's NICU stay will be like and how long it will last by her gestational age at birth.

First, the good news: Advances in medical care mean the outcomes for preterm babies have improved in recent decades, and even the smallest of babies have a greater chance of surviving and living healthy lives. Nevertheless, giving birth early can feel overwhelming. Will your baby be okay? How long will she stay in the neonatal intensive care unit (NICU)? What’s the long-term outlook?

While the answer to these questions depends on a number of factors, making it difficult to give a definitive answer, arming yourself with general knowledge of outlooks by birth date can help you to feel more in control and better prepared to handle your baby’s hospital stay.

How Preemies Are Categorized

Your preemie’s care, length of stay in the NICU and chances of complications depend on the category of preemie he is. In general, the earlier your baby is born, the longer and more complicated the stay in the NICU. The general categories include:

Extreme(ly) preterm: Less than 28 weeks gestation.

Very preterm. Babies born from 28 to 31 weeks gestation.

Moderate preterm. Babies born from 32 to 33 weeks gestation.

Late preterm. Babies born from 34 to 36 weeks gestation.

Early term. Babies born from 37 to 39 weeks gestation.

Premature babies aren’t only categorized by gestational age. A preterm baby’s health and treatment in the NICU also has a lot to do with size at birth — usually the smaller the baby, the greater the chances for a longer hospital stay and possibility for complications:

Low birth weight are those babies born weighing less than 5 pounds, 8 ounces.

Very low birth weight are those babies born weighing less than 3 pounds, 5 ounces.

Extremely low birth weight are those babies born weighing less than 2 pounds, 3 ounces.

Micro preemies are the smallest and youngest babies, born weighing less than 1 pound, 12 ounces (800 grams) or before 26 weeks gestation.

The Outlook for Extreme Preemies (Born Before 28 Weeks)

According to experts at the American Academy of Pediatrics (AAP), the survival rate is 80 percent for extreme preemies (born before 28 weeks). That rate drops about 10 percent for each week earlier a baby is born (i.e. still about 80 percent for babies born at 27 weeks and 6 days, and 70 percent for those born at 26 weeks). At 24 weeks, extreme preemies have a 50 percent chance of survival.

What happens in the NICU?

Because their respiratory systems aren’t fully developed, these tiny babies need help breathing. And since the ability to coordinate reflexes like sucking and swallowing doesn’t kick in until around 34 weeks gestation, they aren’t able to eat on their own; most receive nutrition and fluids intravenously (through an IV). Most are extremely low birth weight, so they’ll need to gain a few pounds. Additionally, extreme preemies are at an increased risk of complications, including respiratory distress syndrome (RDS, a lung disorder), hypoglycemia (low blood sugar), hypothermia (difficulty staying warm), jaundice, urinary tract infections, and pneumonia, all of which can increase the amount of time a baby needs to stay in the hospital.

How long before your baby can go home?

Even extreme preemies without complications are typically ready for discharge two to three weeks before their due date. But babies who have endured health complications as a result of their preterm status, such as breathing problems or difficulty gaining weight, may have to stay in the NICU well after their birth date. Generally speaking, the earlier the baby is born, the more likely she will have to stay past her due date. But new parents shouldn’t get their hopes dashed when baby has to stay a little longer. Soon enough, your little bundle will be ready to go home.

The Outlook for Very Premature Babies (Born Between 28 and 31 Weeks)

The survival rate for very preterm babies is around 95 percent. Babies born before 32 weeks have the most breathing difficulties. Although older preemies are still at risk for complications, the odds are much smaller that they'll have them.

What happens in the NICU?

Babies who have breathing difficulties will likely need to be placed on a respirator for a while. Some have trouble feeding and may initially receive their meals through a tube that’s inserted into the nose or mouth and passed down to the stomach (this is called “gavage” feeding). Because their immune systems are still developing, they’re also at a greater risk of infection, and they’re more prone to hypoglycemia and hypothermia.

How long before your baby can go home?

Babies born at this age usually go home a couple of weeks before or right around their original due date, as long as they don’t experience any serious complications or illnesses.

The Outlook for Moderate Preemies and Late-Term Preemies (Born Between 32 and 36 Weeks)

Moderate and late-term (or near-term) preemies have spent quite a bit of time in Mom’s womb, so the odds for their survival are about 99 percent or more.

What happens in the NICU?

Most babies in this category are less likely to have severe breathing problems (thanks to some development of lung-maturing surfactant in utero), but they may need help with breathing for a few hours or days. Some may require gavage feeding, but most will be able to nipple-feed. As with any preterm baby, they’re still at risk for infections and problems like jaundice, hypoglycemia and hypothermia.

How long before your baby can go home?

It depends: Anywhere from just after birth to a few days or a few weeks. If all checks out with your baby, he may be able to go home right away. But if there are any issues, your baby will have to stay for a (likely very short) while.

The Outlook for Early-Term Babies (Born in Weeks 37 and 38)

For decades, “full-term” described any pregnancy that lasted until at least 37 weeks. But a few years ago, the American College of Obstetricians and Gynecologists (ACOG) changed the definition. Now a full-term pregnancy is considered between 39 weeks and 40 weeks, 6 days. That means a delivery that occurs between 37 weeks and 38 weeks, 6 days is referred to as an “early-term” delivery. These early-term babies still have a risk of infections and other problems, but the odds of complications are very low.

What happens in the NICU?

At this point, babies are usually right on track developmentally, so any treatment will be minimal.

How long before your baby can go home?

Many babies in this category don't have to spend any time at all in the NICU. At most, it will likely be a couple of weeks tops.

Getting Clearance to Go Home

No matter your baby’s gestational age at birth, she must meet a few requirements before her doctors will determine it’s safe to take her home. She must:

Breathe on her own

Maintain a stable temperature

Feed by breast or bottle (although some babies with feeding tubes are cleared to go home under certain circumstances)

Reach a certain weight and be gaining weight steadily

Have no unresolved acute medical concerns such as apnea (when preemies stop breathing for short periods of time while they're sleeping)

Until your baby meets these requirements, she’ll have to stay in the NICU for monitoring and care. But once your baby meets all these criteria, and barring any other complications, you’ll be able to bundle her up, take her home and enjoy your new life together.

From the What to Expect editorial team and Heidi Murkoff, author of What to Expect the First Year. Health information on this site is based on peer-reviewed medical journals and highly respected health organizations and institutions including ACOG (American College of Obstetricians and Gynecologists), CDC (Centers for Disease Control and Prevention) and AAP (American Academy of Pediatrics), as well as the What to Expect books by Heidi Murkoff.

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James Cummings, MD, Chairperson for the AAP’s Committee on Fetus and Newborn, Albany, NY